This invention relates to a reservoir tank structure for storing the brake fluid of a master cylinder, more specifically means for preventing brake fluid from dropping from or coming out of a disengaged and tilted cap of the reservoir tank onto the outer peripheral surface of the reservoir tank.
A conventional master cylinder reservoir tank structure as shown in FIG. 1 is known in the art, wherein a cup-type reservoir tank 1 is mounted on a master cylinder for a brake control system (not shown) with brake fluid 2 being stored within the reservoir tank 1. The reservoir tank has a rib 3 formed therein at the lower portion thereof, on the upper surface of which a hat-shaped filter 5 is placed having rib 4 formed therein. A cap 8 is screwed onto the upper outer periphery of the reservoir tank 1 to cover the upper portion of the reservoir tank. An oil seal case 9 is received within and mounted on the cap 8 and comprises a base 10 having a disk shape, a cylindrical oil seal receiving portion 11 formed along the outer periphery of the base 10, and a disk-shaped baffle portion 12 formed just below the base 10. Formed on the outer peripheral surface of the oil seal receiving portion 11 is an annular groove 13 in which an oil seal 14 is accommodated in resilient engagement against the inner peripheral surface of the reservoir tank 1.
The above described conventional master cylinder reservoir tank has the following drawbacks:
Jerking or vibrations of the automobile body during driving conditions may cause the brake fluid 2 to splash upwards.
The upwardly splashed brake fluid adheres to the base 10 and the baffle portion 12.
When the cap 8 is disengaged and tilted as shown in FIG. 2 so that the interior of the reservoir tank can be inspected, the brake fluid which adhered to the base 10 and the baffle portion 12 drops off and adheres to the female thread portion of the cap.
When the cap 8 is then mounted to the reservoir tank 1 again, the brake fluid which adhered to the female thereded portion of the cap 8 runs down along the outer peripheral surface of the reservoir tank 1, which may be confused as brake fluid directly leaking out from the tank 1.